Those assessments of the Democratic race are hardly controversial; even Sanders has conceded the delegate arithmetic is stacked against him. But they do reflect new candor about the race from both Obama and Biden, who have remained largely mum about their own party's nomination process even as they take every opportunity to rip Republicans vying for the presidency.

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Upholding impartiality in the Democratic primary was a carefully calculated attempt by the White House to maintain some semblance of party unity, even as Clinton and Sanders divided traditional Democratic voting blocs in their respective bids for the nomination.

It's never been a secret that Obama -- who was Clinton's boss for four years -- regards his former secretary of state as a more natural caretaker of his presidential legacy. Saying that out loud, however, remained off the table in an attempt to disarm Sanders' supporters of their accusations the Democrat establishment was behind his rival.

That meant offering praise in equal doses to both candidates. For every instance of Obama declaring Clinton "wicked smart" -- as he did in a Politico interview in January -- was a separate compliment to Sanders, like when Biden told CNN's Gloria Borger the Vermont senator was a more authentic voice on income inequality.

Through it all, neither man revealed his own leanings -- even though both voted in his home state's Democratic primary. Even Biden's remarks this week didn't reflect an official endorsement, his aides insisted, instead suggesting the comment was simply an assessment of delegate math.

The evenhandedness so far appears to have worked at avoiding major intra-party rifts.

"The vice president and president have been great. Neither have endorsed a candidate. I think that really has helped us a lot," Tad Devine, a senior Sanders campaign strategist, told CNN Tuesday. "I think they both have been fair and that's really the only thing we asked of both the president and vice president."

As the race reaches its final stretch, however, it's clear Obama and Biden view the finish line nearing.

"At some point there's going to be a conversation between Secretary Clinton and Bernie Sanders about how we move towards the convention," Obama said last week.

Officials say neither Obama nor Biden will call for Sanders to drop out, just as Clinton herself has avoided pressuring her rival to leave the race. As Clinton looks beyond the primary contests to general election battlegrounds, discussions are already underway among Democrats on where to deploy Obama and Biden in the bid against Donald Trump.

For Obama, that could mean college campuses, where Clinton has struggled against Sanders. Biden, meanwhile, looks to play a similar role as he has in previous campaigns, appearing in states like Michigan and Pennsylvania where his blue-collar roots appeal to Democrats.

Obama has consistently maintained that Trump won't succeed him as president, and on Wednesday, the White House revealed little fear the billionaire businessman would prevail, despite early polls showing close races in some key states.

"Regardless of what predictions are made about the outcome at this point, the President will be fully engaged in making an argument about having a successor that's committed to building on the progress that we've made over the last seven or eight years," White House Press Secretary Josh Earnest said.

Even before Obama hits the trail for a Democrat, however, the administration is scaling up its attacks on Trump, who cleared the field of Republican rivals to become the presumptive nominee in early May. With Trump's sights firmly set upon Clinton, Democrats hope to counterbalance the impending onslaught of attacks.

For Obama and Biden, that's meant ratcheting up the warnings about the damage they claim Trump is already inflicting on the country's standing.

"I understand what it means to compete in a heated election contest. But by insulting our partners throughout the hemisphere, by tarring all immigrants with a xenophobic brush, some leaders are actively undermining our security and our prosperity," Biden said Wednesday in Tampa, where he was delivering remarks about foreign policy. He didn't mention Trump by name.

Obama's National Security Adviser Susan Rice -- who ordinarily operates outside the political realm -- made similar comments during a graduation ceremony in Florida on Wednesday.

"There are voices out there that disparage our diversity -- that question whether America should welcome people of all races, religions, and creeds," she said at Florida International University. "Those voices can be loud. They can be intimidating. They can make us feel like we don't belong. But, you know what? Let fear be their problem, not yours. Shake it off. Ignore the haters. And, don't you dare let them slow you down."